Handwriting and forensic “science”

So, I really enjoyed watching the Jinx, and I certainly think Robert Durst likely killed all those people, but I was not entirely persuaded by the handwriting analysis that proved to be so crucial to how events ultimately unfolded.  The handwriting expert was given a target item and an item known to come from Durst and looked for similarities and found them.  I get that this is how a lot of forensic “science” works, but the problem is that it’s not actually science.  Oh, I do think it is indicative and telling.  But that’s it; nothing more.  Certainly not “scientific” evidence that would prove something beyond a reasonable doubt (e.g., DNA).

Actual science (and good social science!) seeks to disconfirm hypotheses, not confirm them, as is the case in the handwriting analysis.  A genuinely scientific analysis would try and rule out everybody except Durst, leaving no conclusion but that he must be the writer.  That’s how DNA works, you are essentially ruling out billions of other people until the only reasonable conclusion is that you have the DNA of the actual subject.  And, that’s what science is about– ruling out other possible explanations until you are left with a sole reasonable one.  And, of course, why science is never truly done, because you can always find more explanations to rule out.

Anyway, I’ve written plenty about the lack of science in forensic science, but actually seeing that handwriting analysis seeking confirmation, rather than disproof, really struck me while watching the Jinx.  And this forum in the NYT about the matter and how we judge forensic science gave me a good excuse to write about it.  For me, this is the key contributor:

The National Commission on Forensic Science was formed in response to widespread concerns that forensic evidence that lacked any meaningful scientific basis was being regularly permitted in trials. The concerns were not just about the “expert” witnesses, but about the judges who, according to the National Academy of Sciences report that led to the commission’s creation, have been “utterly ineffective” in assessing the quality of research behind the evidence.

And, it wasn’t that long ago, but can never really link too often to Radley Balko’s terrific series on how much junk forensic science there is and how it gets way to much respect from judges.

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About Steve Greene
Professor of Political Science at NC State http://faculty.chass.ncsu.edu/shgreene

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